To overcome a disadvantage that a user needs to press a button or a handle to allow a conventional water spray gun to continuously spray water, referring to FIGS. 7 to 9, a kind of water spray gun, as disclosed in my previous invention, comprises a main body (50), an axle bolt (60), a mounting unit (70), a control unit (80) and a sealing cover (90). The main body (50) has a handle (51) and a barrel portion (52) which are connected to each other, and a cover (53) covers around outer surfaces of the handle (51) and the barrel portion (52). Also, a first O-ring (521) is disposed on a front portion of the barrel portion (52), thereby achieving the water sealing-effect of the main body (50). A front end of the barrel portion (52) is connected to a base (54) which is configured to connect to a spray head (55), and a holding portion (56) is connected the handle (51) and the barrel portion (52) at two ends thereof. Furthermore, the handle (51) has a water control chamber (511) laterally penetrating through an upper portion thereof, and the water control chamber (511) is communicated with a water inlet channel (512) of the handle (51) and a water outlet channel (522) of the barrel portion (52). The handle (51) and the barrel portion (52) is connected with an angle, and an outer corner of the connection has an arc surface (513). Moreover, two blocking pieces (514) are respectively formed at an upper end and a lower end of the arc surface (513), and the spray head comprises a plurality of spray holes (551) which are configured to perform different patterns of spraying water such as solid stream, full cone, or other various patterns. In addition, a locating unit (57) comprising at least s spring and a locating column is secured between the base (54) and spray head (55). A first lateral edge of the axle bolt (60) has a water flowing hole (61) which is cut and shaped into a preferred angle, and a through hole (62) formed at a bottom end of the water flowing hole (61) penetrates through an opposite side of the first later edge of the axle bolt (60). The axle bolt (60) is configured to be turned by a user to selectively block the through hole (62) in different levels, thus controlling the on/off operation and water amount of the water spray gun. A first end of the axle bolt (60) has a first peripheral groove (63) which is configured to be disposed by a second O-ring (631), and a second end of the axle bolt (60) is connected to a connecting tube (66) which has a smaller diameter than the second end of the axle bolt (60). Moreover, the first peripheral groove (63) is connected to a first blocking edge (64) which has a larger diameter than the first peripheral groove (63). Furthermore, an inner surface of the blocking edge (64) close to the first peripheral groove (63) comprises two first engaging pieces (65) which are respectively formed at two corresponding positions. Additionally, two second engaging pieces (67) formed in hook shapes are respectively located at a top portion and a bottom portion of an outer periphery of the connecting tube (66). A second blocking edge (71) formed at a first end of the mounting unit (70) has a larger diameter than the mounting unit (70), and the second end of the mounting unit (70) comprises an axial connecting hole (73). An inner surface of the second blocking edge (71) close to the second end of the mounting unit (70) has two blocks (72) which are respectively formed at two corresponding positions, and two engaging holes (74) are respectively formed at a top portion and a bottom portion of an inner periphery of the connecting hole (73). An outer periphery of the mounting unit (70) has a second periphery groove (75) which is configured to be disposed by a sealing ring (751). The control unit (80) has two parallel rotating arms (71), and a pressing piece (82) is connected to the two rotating arms (71) at two ends thereof. Each of the two rotating arms (71) has a stepped hole (83) laterally penetrating through a central portion thereof, and each of the two stepped holes (83) has two engaging slots (84) respectively formed on an inner periphery thereof at two corresponding positions. In assembly process, the sealing cover (90) secured inside the main body (50) located between the water control chamber (511) of the handle (51) and the barrel portion (52), and the two rotating arms (81) of the control unit (80) are respectively borne against two lateral ends of the water control chamber (511) so as to allow the pressing piece (82) to couple and move on the arc surface (513) with a limited displacement. After the control unit (80) is coupled on the main body (50), the two stepped holes (83) are aligned with the two lateral ends of the water control chamber (511) such that the axle bolt (60) is configured to penetrate through the first stepped hole (83), the water control chamber (511), and the second stepped hole (83) to connect to the mounting unit (70). Wherein the axle bolt (60) is firmly connected to the mounting unit (70) through connecting the connecting tube (66) to the connecting hole (73), and the two second engaging pieces (67) are respectively engaged with the two engaging holes (74). In the meantime, the first blocking edge (64) of the axle bolt (60) and the second blocking edge (71) of the mounting unit (70) are respectively coupled in the two stepped holes (83) of the control unit (80), and the two first engaging pieces (65) of the axle bolt (60) and the two blocks (72) of the mounting unit (70) are respectively engaged in the engaging slots (84) on the two control unit (80) such that the control unit (80), the axle bolt (60) and the mounting unit (70) are configured to be linked and moved synchronously.
However, the water spray gun of my previous invention still has its disadvantages because: the through hole (62) connecting to the water flowing hole (61) has a smaller diameter, and it cannot allow a large volume of water to flow through at one time, which limits the volume of spraying water. Therefore, there remains a need for a new and improved design for a water spray gun to overcome the problems presented above.